Spoiler If you kill a jarl.....

[redrkt]

Do you take over as jarl? or get creamed by all the guards?

 

[Seth]

From my experience - "Creamed" by all the guards.

 

[MushroomGenius]

Sure... "murder" a standing King, you get your own Rebellion.... knife a lowly Jarl, get bumrushed by the guards...

 

[Andante]

In my experience, you can't really "kill" a Jarl. They're marked as essential, and only "fall down to recover" instead of actually dying. ...but yeah, if you try, prepare your bum for some Guard creaming.

 

[xSuoiveDx]

The only Jarl you can kill & it is in a Quest is Ullfric Stormcloak if you do the Imperial Quest line.